1. Field of the Invention
The present invention relates to a composite substrate and a method of producing the same.
2. Description of the Related Art
Acoustic wave devices include interdigital transducer (IDT) electrodes formed on one surface of a piezoelectric substrate and pick up a signal in a specific frequency band. In recent years, composite substrates obtaining by bonding a thin piezoelectric substrate to a support substrate with a small thermal expansion coefficient have been used to improve thermal characteristics of the acoustic wave devices. As an example of these composite substrates, a composite substrate is known in which lithium tantalate or lithium niobate is used for the piezoelectric substrate and silicon or quartz is used for the support substrate (see PTL 1).